Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Sat May 19, 2012 6:32 pm

Come on, no way that replacing engine 5 will put the launch back to September. Where did you come up with this? They didn't say that in the conference afair.

They have a (second!) complete F9 down at the cape, so there are at least 9 "spare" engines at hand. Shotwell did actually address this: if it turns out something needs serious fixing, the will likely swap out the entire engine.

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Sat May 19, 2012 7:07 pm

Marcus Zottl wrote:

Come on, no way that replacing engine 5 will put the launch back to September. Where did you come up with this? They didn't say that in the conference afair.

They have a (second!) complete F9 down at the cape, so there are at least 9 "spare" engines at hand. Shotwell did actually address this: if it turns out something needs serious fixing, the will likely swap out the entire engine.

It's from earlier news reports prior to the launch that because of scheduling problems any significant delay in the launch would require it to be pushed back all the way to September.

Bob Clark

_________________Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage. Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines and stages at the same time, and the result will automatically be SSTO.Blog: http://exoscientist.blogspot.com

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Sat May 19, 2012 7:10 pm

In the post launch press conference, Shotwell said this excess heating in the number 5 engine appears to be more than a sensor problem. Also, there were unexpectedly high heating problems with some of the engines during the Dec., 2010 flight, also due to oxidizer-rich conditions (equivalently, low fuel amounts):

The phrasing in these reports initially made it seem like these engines during that flight had to be shutdown prematurely because they were running oxidizer-rich. But what was meant was that all the engines did shut down at the planned time but they occurred under conditions where there was an excess amount of oxidizer, which can result in excessively high temperatures.

Bob Clark

_________________Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage. Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines and stages at the same time, and the result will automatically be SSTO.Blog: http://exoscientist.blogspot.com

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Sat May 19, 2012 7:32 pm

Marcus Zottl wrote:

They have a (second!) complete F9 down at the cape, so there are at least 9 "spare" engines at hand. Shotwell did actually address this: if it turns out something needs serious fixing, the will likely swap out the entire engine.

How about using the other F9 as is? I guess that would call for another test firing, but so would an engine swap, wouldn't it?

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Sat May 19, 2012 11:06 pm

It's interesting that this wasn't detected before during the test firing. And Cape Canaveral is useless as a range, there are always conflicts and delays and issues. SpaceX really need that range in Texas.

_________________Say, can you feel the thunder in the air? Just like the moment ’fore it hits – then it’s everywhereWhat is this spell we’re under, do you care? The might to rise above it is now within your sphereMachinae Supremacy – Sid Icarus

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Sun May 20, 2012 6:20 pm

I think it's something to do with other expensive rockets sitting on their pads with expensive payloads waiting for launch, and the risk of the F9 blowing up on ascent and damaging them. Either that or its just bureaucracy. But SpaceX want to be launching 10 F9s and 10 F9 Heavy's per year, and the way it's going right now flying two rockets in a single year from the Cape appears to be a challenge already. Of course they've also got Vandenberg, but that's also a government/military run range. SpaceX really need their own place that'll let them set things up efficiently.

_________________Say, can you feel the thunder in the air? Just like the moment ’fore it hits – then it’s everywhereWhat is this spell we’re under, do you care? The might to rise above it is now within your sphereMachinae Supremacy – Sid Icarus

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Mon May 21, 2012 8:55 am

I didn't want to imply that I find a third, purely commercial, launch site superfluous. On the contrary I agree with you that it is necessary and would even predict, that such a site would quickly become their most important launch site.

I was really just wondering about the issues to acquire "the range" (as they tend to call it) at CCAFS. I would go with your argument about bureaucracy since I don't know about anybody besides ULA who does regular launches from the cape and they launch how many? 10 a year or something?